Work under this program-project grant proceeds in eight collaborating laboratories, all concerned with mechanisms of neural plasticity in the mammalian brain, with methods drawn from neuromorphology, neurophysiology and experimental analysis of behavior. Progress has been made primarily in three inter-related areas, involving (1) modifiability of feature-sensitive neurons in cortex and brainstem (cats, monkeys); (2) structural changes (e.g., neuronal sprouting) after early cerebral lesions (esp., in hamsters); (3) behavioral adaptation to early b@ain injury or sensory loss (e.g., vestibulectomy) as compared with similar lesions incurred later in life, in animalss and humans. Sample results from each area show (1) that rearing kittens in uniformly striped cylinders does not reliably affect the visual cortex, but rearing with goggles presenting conflicting or even congruent input to the two eyes does. (2) Early lesions of visual or visuomotor pathways in hamsters lead (through sprouting) to false connections; the behavioral consequences of such misconnectios can be reversed by subsequent interruption of the anomalous pathways. (3) Intensive study of recovery from early brain lesions in monkeys and children confirms "sparing" of functions in some neuronal systems but not in others. Accordingly, a search for histologic "markers" of these two kinds of systems has been instituted. BIBLIOGRAPHIC REFERENCES: Bizzi, E. Central control of eye and head movements in monkeys. Pp. 469-471 in: G. Lennerstrand and P. Bach-y-Rita (eds.) Basic Mechanisms of Ocular Motility and their Clinical Implications. New York: Pergammon Press, 1975. Bizzi, E. Motor coordination: Central and peripheral control during eyehead movement. Pp. 427-437 in: M.S. Gazzaniga and C. Blakemore (eds.) Handbook of Psychobiology. New York and London: Academic Press, 1975.